The present technology relates to a light-source circuit unit and an illumination device which include, as a light source, light emitting elements such as light emitting diodes (LEDs), and a display device including the illumination device as a backlight.
The light emitting diodes (LEDs) have been noticed as a backlight (light source) of a liquid crystal display device or a light source of an illumination device in place of an incandescent lamp or a fluorescent lamp. Since LED emits light from surfaces in all directions, a certain reflective surface needs to be provided on the back surface of an LED chip to extract light emitted from the back surface to the front surface. A lead frame or a wiring pattern for supplying a current to the LED chip typically includes copper (Cu). In an exemplary method of extracting light emitted from the back surface of the LED chip to the front surface, a circuit substrate having such a wiring pattern has a white resist layer thereon, and the white resist layer is used as a reflective layer, as disclosed in Japanese Patent No. 4107349. The light emitted from the back surface of the LED chip is reflected to the front surface by the white resist layer and extracted.